Field tests have been performed on a prototype spatially-averaged filter scintillometer designed to measure wind components transverse to an optical path. Unlike previous scintillometers, the spatially-averaged filter design peaks weighting functions at five segments along the optical path, producing simultaneous cross-path wind readings from these path segments. Intercomparison tests indicate that the scintillometer performs well under most meteorological conditions. However, a performance problem was identified during cross-path wind reversals in light and variable winds, where ambiguities in the sign of the crossing wind component occasionally caused spurious wind readings. The calibration factor also needs further testing. The crosswind scintillometer has significant remote wind sensing applications.